1. Technical Field
The disclosure relates to a display.
2. Background
An electrowetting display includes a plurality of electrowetting display pixel structures. Each of the electrowetting display pixel structures includes a barrier, a pixel electrode, an insulating layer, a hydrophobic layer, a polar fluid and a non-polar fluid. The insulating layer is disposed on a surface of the pixel electrode and the hydrophobic layer covers the insulating layer. The non-polar fluid is disposed on a surface of the hydrophobic layer. The polar fluid covers the non-polar fluid. The barrier is disposed on the hydrophobic layer to separate two adjacent pixel structures.
When a voltage is applied to each of the electrowetting display pixel structures, the polar fluid is driven by an electrostatic force to contact the pixel electrode. The non-polar fluid is then propelled to a corner corresponding to the hydrophobic layer of the pixel. Here, the position of the non-polar fluid is determined according to the design of various pixel electrodes. Generally, the non-polar fluid is a colored non-polar fluid medium such as oil or other material. The non-polar fluid is colored by using a pigment or a dye. The polar fluid medium is a colorless polar fluid medium such as water, alcohol, or so on. Thus, after the light passes through the non-polar fluid colored with a dye, the light is absorbed by the dye in the non-polar fluid to show a color of the dye in the non-polar fluid. On the contrary, the light passes through the transparent polar fluid. In other words, when a voltage is applied to the electrowetting display pixel structure, the polar fluid contacts the electrode so as to push the non-polar fluid to the barrier. Hence, a grayscale change in display can be carried out by converting the electrowetting display pixel structure between a voltage applying state and a no voltage state, such that the electrowetting display displays an image.
In order to ensure the consistency of a contraction of the non-polar fluid, a patterned pixel electrode is adopted for limiting the non-polar fluid to a corner of each of the electrowetting display pixel structures to achieve the above image display. For example, as depicted in FIGS. 1A and 1B, a pixel region 114 includes a distribution region of pixel electrode 118 and a non-electrode region 116. A pixel electrode PE is disposed in the distribution region of pixel electrode 118 and has an unfilled corner of a ¼ circle (as shown in FIG. 1A) or an unfilled corner of a ¼ rectangle (as shown in FIG. 1B) corresponding to the non-electrode region 116. The patterned pixel electrode of these shapes can increase the conversion speed of the electrowetting display pixel structure between the voltage applying state and the no voltage state.
FIGS. 2A to 2E are three-dimensional schematic diagrams illustrating a contraction process of a polar fluid converting from a no voltage state to a voltage applying state in an electrowetting display pixel structure having the pixel electrode PE shown in FIG. 1A. Referring to FIGS. 2A to 2E, it should be noted that when the electrowetting display pixel structure is driven under a higher voltage to increase the response speed, configurations of the patterned pixel electrodes PE may cause the fragmentation of the non-polar fluid 134 (represented by even dots) during the contraction process (shown by the breakage in FIG. 2D). The non-polar fluid 134 then gradually contracts back to the non-electrode region 116 of the electrowetting display pixel structure after a period of time. The fragmentation process of the non-polar fluid 134 may lead to decreasing aperture rate of the electrowetting display, increasing response time, increasing complexity in the design of driving system, and poor display quality.